"So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth." (Rev. 3:16) “To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact” (Charles Darwin)

Yesterday we looked at his first test. I finished the exercise believing that we could in fact convince Mr. Ridley, given time and attention, that the question was answerable in a way that would support green policy measures to some extent. (Not everyone agrees with me–see the comment thread.)

Today we’re on to Mr. Ridley’s second question–“Despite these two contaminating factors, the temperature trend remains modest: not much more than 0.1 C per decade since 1979. So I would need persuading that water vapour will amplify CO2’s effect threefold in the future but has not done so yet. This is what the models assume despite evidence that clouds formed from water vapour are more likely to moderate than amplify any warming.”

This is the toughest question for ardent activists to answer and I have posed variations of it here on this blog–as have many other scientists, reporters and bloggers.

Because we don’t know at all what the sensitivity of the atmosphere is to a doubling of the concentrations of CO2, we cannot show Mr. Ridley a mathematical proof, a historical record or even accurate model outputs. So far we express our estimates of sensitivity as a range–the IPCC sets the parameters of this range at between 1.5C and 4.5C. If Mr. Ridley insists on one certain value we should just say frankly that we cannot persuade him and wish him well going forward.

As someone who believes that we require something in the way of a green policy oriented towards global warming (even if my ideal might differ dramatically from what’s on offer today), I would try and continue the conversation with Mr. Ridley if he were willing.

Taking the temperature since 1979 captures one period of rapid warming and one period of stasis. Averaged together they show a very tolerable level of warming if continued throughout the century. And this record certainly is not convincing evidence of a high level of sensitivity of the atmosphere.

However, given the multitude of forces that interact to move atmospheric temperatures up, down and sideways, we’ve always known that average temperatures could stall for an extended period between rises–they can even dip. As has happened during the Age of Thermometers. So I would look at more of the past and spend time trying to look into the future.

This isn’t a problem of theory–which strongly suggests that there is some level of sensitivity to rises in CO2–it’s a problem of attribution. How much of the rise from 1979 to 1998 is due to CO2, how much of the stasis since then is due to ENSO periodicity and strength, etc. We don’t know the answer to that. And if uncertainty invalidates any action for Mr. Ridley then he will end up an opponent of green policies. And again, that doesn’t make him an enemy of the human race or a bad person. He’s just an opponent in a political struggle.

Almost every scientist who has tried to calculate sensitivity of the atmosphere to CO2 has come up with a positive number for it, from Svante Arrhenius (who I think actually came up with 4 values in 4 different calculations, ranging from 2.1C to more than 6C) to James Hansen to self-proclaimed skeptic Richard Lindzen (who has variously estimated sensitivity at between 0.5C and 0.8C). Those most inclined to be activists found higher values, those most inclined to either Lukewarm or skeptical status found lower values. But that it is a positive is the norm.

Until that happy day I will remain of the opinion that in 2075 the world will be using six times the energy that we used in 2010 and that most of it will be provided by burning coal. In addition to the problems of conventional pollution and black soot this will cause, it will also emit incredible volumes of CO2.

And my fear is that even with a low sensitivity, when combined with a confluence of upward movements in the other various cycles affecting our temperatures ranging from ENSO to solar cycles to even our progression through Milankovitch cycles, that there will be a pronounced effect on temperatures.

So I would say to Matt Ridley that he has identified the area of weakness that must be addressed if climate science is to provide definitive answers instead of provocative questions. I don’t have the hard answers he may require to enlist his support in efforts to contain our contributions to climate change, and I honestly don’t think anyone else does, either.

But if he is unwilling to make even a modest provision for an uncertain future, given what little we do know, that will make Mr. Ridley, much as I respect him and admire what he’s written, my political opponent in this struggle.

Science writer and occasional climate commentator Matt Ridley has published a list of ten questions he feels need to be answered before he is convinced that ‘current climate policy makes sense.’ As the title of his essay is ‘A Lukewarmer’s Ten Tests’ I feel honor bound to at least look at them. It’s easy–Ridley’s a fine writer and his exposition is organized and clear.

The first question he wants answered is: ” I need persuading that the urban heat island effect has been fully purged from the surface temperature record. Satellites are showing less warming than the surface thermometers, and there is evidence that local warming of growing cities, and poor siting of thermometers, is still contaminating the global record.

I also need to be convinced that the adjustments made by those who compile the global temperature records are justified. Since 2008 alone, NASA has added about 0.1C of warming to the trend by unexplained “adjustments” to old records. It is not reassuring that one of the main surface temperature records is produced by an extremist prepared to get himself arrested (James Hansen)”

Much as I am hoping that Mr. Ridley brings some reason and clarity to this debate, as he did with his excellent book The Rational Optimist, I think he starts off poorly here.

What we measure to understand global warming is changes in the temperature not the beginning and end readouts of a thermometer. The Urban Heat Island effect is real. Time of observation for keeping records have changed. The physical location of measurement stations have changed.

All of this (and more) is well-known and well-discussed by scientists. Most recently, Richard Muller and his team tried to revisit this question–and to the best of my knowledge, improved on the understanding of these issues considerably. What they found was clear evidence that nobody is manipulating the figures to pump a little extra global warming in there for political purposes.

Not to say there are no errors. There are. And when scientists find errors in the data, they talk about them and introduce corrections into the data series. Our friends in the skeptic community notice immediately when those corrections push temperatures up–but corrections often adjust them downwards as well.

The central point is that the start and end point of a temperature reading is almost irrelevant to the exercise. If the measurement accurately captures the amount of change, for understanding climate change it doesn’t matter so much whether the change is from 11 to 12 or from 11.5 to 12.5. What matters is that the one degree change is accurately captured.

And we have pretty good evidence that, using correctly sized error bars and admitting the level of uncertainty, we are indeed capturing the change. And that it is not imaginary. And that it is not a political invention.

Steve Mosher (who worked with Muller on his ambitious temperature re-measurement project) and I wrote a book on Climategate a couple of years ago. Two of the central issues there involved temperature measurements. (The second involved tree trunks, not thermometers and is for another day…)

The first problem we found was in a 1990 paper published by Nature and written by Phil Jones (who later advised colleagues to delete emails). The paper was written to minimize the worries about UHI (the Urban Heat Island effect) and used temperature records from different countries to ‘show’ that UHI was vanishingly small.

Sadly, Jones didn’t issue a correction and his paper sat out there for years. It was famous and frequently cited as ‘proof’ that UHI was not a real issue. (This was actually what led to Climategate, through a rather complicated chain of events.)

It was only fifteen years later that Jones published a new paper showing a higher figure for UHI. He never issued a correction for his earlier paper, despite knowing it was wrong for more than a decade.

But even with his ‘mistake’ regarding UHI, it did not affect consideration of climate change overall. Even his new, higher calculations for UHI are not huge. Moreover, most of the earth’s surface is covered by water and UHI doesn’t affect oceans or lakes. And a surprisingly modest percentage of the land on this planet is subject to UHI–we don’t find much of it in either Antarctica or the Sahara.

So, Mr. Ridley–early mistakes caused us to underestimate the effects of the Urban Heat Island effect on temperatures of cities (and smaller population aggregations as well). It had an effect on the temperature record. Some scientists behaved poorly in regards to analysis of this issue.

But it did not mask the changes in temperature over time. And it wasn’t large enough to introduce a spurious signal that was mistaken for global warming.

I think there’s a rule about not capitalizing the title of a post when it gets to be as long as the post itself…

I am hoping to do a series of posts on Matt Ridley’s essay published via GWPF yesterday. But first, let’s discuss my impressions of a bandwagon effect regarding the Lukewarmer position on anthropogenic climate change.

It seems that the term itself is being more widely used and that more people are identifying themselves or others as Lukewarmers. I think it’s overall a good thing–although I don’t at all take it as a sign that we are winning the argument. Far too early for that.

I think it’s good even though I also think that some people on both sides are playing fast and loose with the term. I think some skeptics are saying that in essence they are Lukewarmers because they accept the accepted physics leading to a 1C per doubling of CO2 concentrations, although in practice they are very skeptical of any further effect on the climate or the rest of the planet. Given the abuse they have received under the name skeptic and the disgusting conflation of skepticism with neo-Nazi skinheads who deny the Holocaust occurred, it’s certainly understandable.

I also see that some climate activists are eager to lump Lukewarmers in with the most ardent of skeptics, arguing that at the end of the day we are as ‘bad’ as their arch-villains like Morano and Monckton. And I understand that–we probably are more dangerous to their position than those at the end of the spectrum and given the way they treat all who are not completely committed to their cause, it would be laughable to expect fair or even honest treatment from people like Eli Rabett or William Connelly, let alone the Tim Lamberts of the world.

I want to get a couple of words in before the wholesale criticism of ‘Lukewarmer-ism’ gets out. I noted yesterday that Dana Cook Nuccitelli (sorry, all) of Skeptical Science plans a post on the folly of the Lukewarm position and I have no doubt that others will be writing against what we generally believe–although most of it will be tied to Ridley’s essay, it will be used as a springboard.

There are already attacks on Lukewarmers out there–most of them purely political and without showing any signs of having read what we have written in various venues. Clive Hamilton labels us as ‘insidious’ (read the comments for my own and Steven Mosher’s response), saying we are ‘politically conservative’ (I’m pretty much to the left of Marx–I just forget if it’s Groucho or Karl), and that we fell for the ‘climategate spin,’ not realizing that almost all of those he accuses of the sin of Lukewarmer-ism were writing long before Climategate.

The most accurate self-description on the intertubes is found at Idiot Tracker–he tracks and he’s pretty much described himself. In his diatribe against Lukewarmers, he manages to combine Steve Mosher and myself into one person named Steve Fuller–although he may have another post somewhere railing against Tom Mosher. There are others–here, for example. (Update: Hey, Idiot Tracker–if you ever see this check above–I just did the same thing with Dana Nuccitelli. Guess we’re all human…)

My basic point here is that the Lukewarm ‘position’ (it isn’t really all that well-defined) is in fact a range of opinions–I’m pretty sure that Steve Mosher and I look at it differently and that Pat Michaels, who identifies himself as a lukewarmer, would disagree with both of us–and maybe Lucia Liljegren, one of the very first to wear the lapel button, might differ from all of us.

It describes a range of opinion. In that it is no different from the labels ‘skeptic’ or ‘climate activist.’ There is a very wide spectrum of opinions on climate change, its various causes and its potential impacts.

What we will see in the coming weeks is an attempt to pigeonhole us. These attempts will come from the extremes of the spectrum. The most ardent of activists will try and push us over with the most skeptical of the skeptics–and it’s quite possible that the skeptics will try and paint us as activists in sheeps’ clothing.

For my money, the most energetic of the climate activists are very wrong in trying to panic the public with talk of Xtreme Weather, a rapid melt of the Greenland Ice Cap, very large rises in sea level and skyrocketing temperatures.

For my money, the most skeptical of the skeptics are very wrong in ignoring the very real potential for future effects on our climate (and the rest of the planet) due to human causes, among which is emissions of incredible quantities of CO2.

But I have no doubt that I (or someone who believes as I do) will be compared to both Michael Mann and Marc Morano–maybe in the same comment thread.

It’s good and I’ll talk more about his various points later, but I thought I’d put this up to start the ball rolling.

Some quotes:

“…the temperature trend remains modest: not much more than 0.1 C per decade since 1979. So I would need persuading that water vapour will amplify CO2’s effect threefold in the future but has not done so yet. ”

“The one trend that has been worse than expected – Arctic sea ice – is plausibly explained by black carbon (soot), not carbon dioxide.”

“Nor is it clear that ecosystems and people will fail to adapt, for there is clear evidence that adaptation has already vastly reduced damage from the existing climate – there has been a 98% reduction in the probability of death from drought, flood or storm since the 1920s, for example, and malaria retreated rapidly even as the temperature rose during the twentieth century.”

If I have time I’ll break each of his ten tests into separate posts for more discussion. I agree with about seven or eight of his points and would quibble on the others.

Before the introduction of agriculture our hunter gatherer ancestors had the habit of burning large tracts of open plain to drive animals before them, hopefully off a cliff where they could be skinned and butchered.

Burning the fields changed the behavior of animals and the growing patterns of plants and trees. It changed the albedo of the Earth itself and the movement of the winds above it.

Beavers dam trees and ruminants paw through the snow to get at the grasses underneath. But when we began farming our treatment of land and rivers was an organized and systemic change to the environment. Now we have 800,000 dams built and 33% of habitable land is under the plough. The reservoirs behind the dams have a different albedo than the land they covered and the humidity also changes the wind patterns around it. And the land ploughed under every spring is dark and heat absorbing while the crops at summer’s end are usually lighter in color and are certainly absorbing CO2.

So I don’t think there’s any question that we have changed the climate throughout pre-history and history. I would put the beginning of the Anthropocene at somewhere between 50,000 and 13,000 BCE. And of course it continues today and has grown stronger, with roads, pollutions and emissions of CO2, with jet contrails, canals, megacities and deforestation.

The question is, will our impacts on the environment (including the climate) end in tears?

As regular readers probably already suspect, I’m more optimistic than many others who have looked at this topic. (I studied anthropology during my brief sojourn at the university and have retained a very real interest in it since. I’m not an expert but I have followed closely their explanations.)

It is my conviction that in some areas we are already past the period of our peak influence on the environment and in others that we are approaching that peak.

Specifically, we seem to have reached a peak of how much land we are using for agriculture–the worthy world organizations don’t predict that we will be taking more land for farming.

Also, residential use of land is being concentrated in the large cities of the world, with greater percentages of the population living in urban environments and smaller percentages in rural–and both trends and human desire for advancement make it look as though that will continue.

As we make progress in the developing world, deforestation should slacken–especially if we realize that biofuels are not really a force for good–because those living in the developing world will gain access to electricity and fuels with higher caloric density than dung or branches.

As for climate–well, that is the topic of the millenium to date, and it receives a lot of attention. I’m a Lukewarmer. I think atmospheric sensitivity is lower than many activists and a majority of scientists (although the tide seems to be turning and low sensitivity is becoming more acceptable as a forecast).

But I’m still concerned. Even a low sensitivity of our atmosphere to concentrations of CO2 leave us vulnerable to what will happen in the next fifty years.

I’ve spent a year detailing why on the other blog I maintain, where I forecast (and show my work) that human consumption of energy will be six times as great as in 2010 by the year 2075. That’s why the blog is names 3,000 quads–that’s how much energy I think the world will burn in 2075, compared to the 523 we used in 2010.

Even a very low sensitivity of the atmosphere will not allow us to ignore the effects of that amount of energy. Worse, because other forecasts are much lower (the DOE thinks it will be less than a thousand, although they didn’t update their forecast last year…) we are not putting the infrastructure in place to allow the energy to be provided by anything other than mountains of coal. And that’s the real threat to us.

But the scope of the threat is not at a planet-busting level. As I’ve written before, it may produce a wetter and wilder world–but it will still be recognizable and both life and civilization will go on. So will development, and when population peaks right before the end of the century, no less an august body than the IPCC also predicts that our emissions will begin to decline. We are definitely not talking the end of the world here.

And that’s when this conversation will get interesting. When population has not only stabilized but achieved a decent level of income and access to technology–when 80% of the population lives in cities and much of the planet has returned to nature–what then will we decide to do with our planet?

Update: Planet 3.0 was kind enough to publish my comment on their website on January 30th, five days after it was made. I extend my thanks to them for allowing the publication of my comment.

As the climate debate heated up in the early 2000’s a number of activists, scientists and commenters started up their own weblogs.

Some of them are quite good–best of breed is clearly Bart Verheggen’s weblog “Our Changing Climate“–but others clearly are more interested in politics than science.

What most of them have in common is the ‘Crossfire’ approach to dealing with disagreement–insults are common and dismissal for lack of scientific credentials even more so.

However, the worst tactic in evidence is the censorship of comments and commenters. The ‘moderators’ of these blogs will cheerfully trash your comments, or delay them so the conversation has moved on by the time they appear, or worst of all, ‘edit’ them.

For some reason the operators of these blogs seem to feel that censoring conversations in some way advances the debate. I don’t think the current state of the debate provides much evidence that they’re correct.

As it happens, I have had a comment in moderation for two days now at Planet 3. I’ll post the entire relevant comments below–please offer your reasons on why my comment deserves to be held out of public view…

“But people are reluctant to give up their pet hypothesis, and never develop a real theory. For example, people who love technology, markets and economics will usually persist in believing those change the world, even when they don’t. Others strongly believe in political change, and persist in believing that, even if evidence suggests otherwise.

I tend towards an economics and technology bias, I guess, while others lean towards the political and cultural side of things.

My instincts tell me that we’re probably all wrong, and all right, and it will take some unusual combination of all of these theories to make a real difference in the world.”

If we Cornucopians can add a note to this, there seems to be ample evidence that the world has changed for the better following the introduction of technology and the adoption of science as one of the principal tools for understanding our universe.

With those who do not believe the world has gotten better there is no point in arguing.

For those who believe it is politics or culture that drives change, I would offer the theory that you are looking at lagging rather than leading indicators.

Of course this is totally dependent on how ‘better’ is measured, but there is one fundamental, over-riding sense in which I think it isn’t better – that we are likely facing potentially catastrophic impacts from anthropogenic climate change and we have little prospect of averting that within timescales that would make a significant difference. If it weren’t for this looming threat and the utter sense of lack-of-controlledness my life would be exceptionally comfortable. I can also see progress in so many areas of development, nothing like the pace or consistency of progress I’d like, but something worth working for. But overall I think an objective analysis shows that my life is worse than it would have been when the threats to our stable lives were localised.

Naturally this is only a shadow of my argument, but we cannot ignore prospects for the future when analysing quality of our present.

This is the debate I have been hoping to participate in here at P3, so bless your heart for bringing it up.

I am a Lukewarmer by avocation. (Essentially that boils down to being convinced that sensitivity of the atmosphere to a doubling of concentrations is much lower than 3C. I personally think it’s around 2C and have advocated preparing for 2.5C to give us a measure of additional security.)

Reading the IPCC AR4 and Nicholas Stern’s Review of the Economics of Climate Change shows a possible world that will struggle to deal with climate change, but does not hint at the ‘catastrophic impacts’ that worry you.

As a ‘Cornucopian’, ‘techno-optimist’ believer in what science and technology have already brought us and look certain to bring us in the future, I quite obviously would differ with what you think an objective analysis would produce regarding quality of life measurements.

I would be eager to continue this discussion if it falls within the boundaries of P3 rules and goals.

But Tom, your optimism relies on three things all lining up: that sensitivity is relatively low; that the impacts will be linear (or not severe); that technology will be developed to solve the problems in time. I’d say the probabibility of the last is high, of the first is at best medium and of the middle is low.

Assessing impacts is always going to be difficult, but I see good reason to believe they are going to be worse than you suggest. We can’t rely on peer-reviewed evidence because to all intents and purposes there isn’t any, and it’s difficult to see how there could be. But how could the sort of changes in growing conditions, availability of water and so on we can expect, even with lower sensitivity, not reverse the positive developmental changes we can see happening?

I think I would like in a perfect world to comment almost line by line to your response. I’ll start with the bottom and see where I run out of steam.

Most of the developmental changes we’ve seen have been put in place precisely to counter the forces you think will be exacerbated by climate change. People have been working to address the impacts of drought and flooding and even variability for more than a century. We will have to spend more and spend more wisely to deal with impacts, but so far it doesn’t appear that we’ll need to invent new technologies or bring infant tech to maturity in 30 minutes or less.

We’ve been bringing water to where we want it for millenia now, and we’ve actually gotten better at it than the Romans–although I admire their style. Farmers have also changed cultivars and landcare practices in response to both short and long term changes. There is 5,000 years of best practice available to learn from. We have examples of dealing successfully with sea level rise and not just from the Dutch. Parts of Tokyo have faced 15 meters of relative SLR due to subsidence–but they’re still there.

I would urge you to remember that the bulk of development for the developing world is going to happen during the decades before the net impacts of climate change are projected to turn negative. Remember that at the beginning, even for a 3C rise, there are real winners from the changes we expect through at least 2040. The gains can be used to build resilience into communities and even regions.

Even though I don’t think we need new technology to address these issues, new technologies will certainly emerge. And that’s what I think isn’t linear–new tech will surprise us somewhere in this area, far more than any discontinuity in impacts. Think of the Mole now guarding Venice from the Adriatic or the flood barriers on the Thames as first gen examples that NYC can learn from.

During the next two decades, at least, my conception of lower sensitivity is the least important of the three elements we’re discussing. Even if you’re correct and I’m wrong,the impacts of higher sensitivity are far enough out there that we have time to do what we need to do.

But that’s if we are intelligent enough to abandon some of the memes driving the political battle. You correctly see the flaws and political goals of people like Morano and Monckton. And that’s a good thing. But you transfer that across the spectrum of those who oppose you like spreading peanut butter on bread. That’s inappropriate.

Every day you all work at establishing the Xtreme Weather meme is a day lost to effective consideration and preparation. Worse, it falls into the class of argument that contains many of the skeptical objections–it is a-scientific and aimed at emotion rather than analysis.

There is credible discussion of atmospheric sensitivity that points to a lower value than has been taken for granted. If true, this would lower the threat level that climate change poses to us–or at least buy us extra time to prepare for it.

James Hansen has baldly stated what everyone saw but few on his ‘side’ could bear to admit–temperatures, expected to continue the rise shown between 1976 and 1998, have ‘stalled’ and we really don’t know why.

I happened to run into CDIAC’s estimates for human emissions by year and noticed that one-third of all human emissions had occurred since the period when temperatures stalled–which is not a point in favor of higher values for sensitivity, to say the least.

And today we see from the journal Nature that new Greenland ice cores from 125,000 years ago show that, although there is melting of Greenland ice when temperatures get warmer, that melt is not as extensive as scientists had feared. This may cause us to re-evaluate what will happen with Greenland’s ice if and when our current warming period resumes.

Taken overall, this is good news for humanity. I don’t at this point really care who is advantaged in the debate between activists and skeptics, although both will find reasons to take comfort and attack the other side, I’m sure.

I am having trouble remembering a period that saw such a bang-bang series of released information with the potential for having such a large impact. Readers can help me, and I hope you do.

What surprises me is the lack of discussion about this. Each of these ‘stories’ seem to have lasted about a day. None of them seem to have changed anybody’s mind. The discussion of climate change this year, in major media, mainstream blogs (such as Kevin Drum or Andrew Sullivan) and climate specific blogs doesn’t seem to have absorbed the impact of these stories. In fact, much of what I’ve read about climate change this year could have been pasted in from prior years–or typed in by a robot.

Has climate change become just an icon to which we all must bow, but not one which requires further thought? Readers can help me on this as well…

Keith Kloor’s weblog Collide-a-Scape is a place I hung out in for a couple of years between my own blogging experiences. For a while, Keith was pretty focused on climate issues–he got picked up by Discovery and has (much to his relief, I’m sure) widened his scope significantly. He has run one of the best blogs in the biz for several years now and more power to him.

Keith returned to the subject of labeling recently, specifically the new craze for calling your political opponents anti-science. In the climate change debate, it’s not unusual for either side to employ as the epithet du jour. However, I’d like to focus on the more common term used by climate activists against their opponents–the word (and its variants) ‘denier.’

It gained currency after the journalist Ellen Goodman used it about those skeptical of climate change, likening them to skinhead neo-Nazis in the UK who, among other nastinesses, staunchly maintained that the Holocaust never occurred. It became and still is popular.

It’s obviously hate speech, of course, but a surprising number of climate activists can’t let go of it. They use all the tired defenses of the term that were used by those who thought it was okay to call black people the ‘n’ word, Jews kikes, Hispanics spics, ad nauseum. (I am not for a second saying the term ‘denier’ is anywhere near as harmful or hurtful. It is not. But the process works in the same way.) They said the word antedated its hijacking. They said that it was the plain truth. They said that some of those so accused had embraced the term.

They didn’t seem to accept the modern truth that those who use derogatory language are not the ones who can define its level of vitriol and hatred. That is better left to those on whom the label is used.

But the term ‘denier’ goes beyond insult. It is part of a code that very consciously defines the user. There is a structure to the writings of climate activists, from the speechifiers like Al Gore or Bill McKibben to the bloggers like Eli Rabett and Joe Romm to the various commenters that serve as their shield and sword. It includes pseudo-scientific terms such as the Overton Window and the Dunning Kruger syndrome and is populated with references to pop culture. There was a time when you couldn’t get through a comment thread without being exposed to at least one YouTube clip of Monty Python.

Their communication is to a surprising extent aimed at other members of their tribe–they’re not interested in converting the wicked skeptic or engaging in the occasional newcomer to the debate. They are essentially counting coup. If you wander from blog to blog, as I do, you would often see commenters and even bloggers recounting their confrontation with evil skeptics in prose somewhat more breathless than deathless.

As a form of self-validation I suppose it works. It is an accepted symbolic structure that marks the user as part of a tribe, someone who shares the values of those back at the activist blogs where the user will return. It’s an effective symbol for many, which I guess is why it’s still in use.

But it says something about the mindset, the level (or lack thereof) of humanity inherent in this tribe, that they would be so happily ignorant of the actual meaning of the word or its effect on its targets.

As others have often asked, what is it that skeptics are held to deny? The existence of climate? Climate change? Human contributions to it? The greenhouse effect? Its magnitude, consequences, duration?

Why is it a blanket term applied to people with extremely diverse views, ranging from Nobel prize winners to distinguished physicists to Monckton and Morano to even, well, me? If you looked at all those tarred with the term you would quickly see that the only thing they hold in common is a belief (in varying degrees of strength) that the science isn’t settled, that the consensus has tried to rush to judgment, that we don’t know as much as some have tried to tell us we do.

It’s a nasty word used by nasty people to deliberately insult and demean those on the other side of a political issue.

Ever since Al Gore (for whom I voted three times for national office) appropriated the line ‘The Planet Has a Fever’ the climate debate has often used medical metaphor as a way of either illustrating or misleading.

In articles, blog posts and especially in comments we see the argument that if a doctor said you had cancer you would listen to the doctor instead of your neighbor with a different opinion. For variety they sometimes use heart disease instead.

But ya know something? The planet doesn’t have a fever. It’s a pile of rock with some water, gases and us perched on the surface. It doesn’t care what temperature it is and there is no optimum for it. As for us, we have labeled the periods in the past with different climates, and the ones we have chosen to label Optimum for us have been as warm or warmer than the present.

And global warming? It’s real and it’s a problem. But it’s not cancer and it’s not heart disease. If we are going to insist on a medical metaphor to use in this debate, let’s use the right one.

Global warming doesn’t threaten civilization. It does threaten rapid development of human potential, economic progress at the margins and the continued progress that has characterized the past two centuries. The solution to global warming is slow, expensive and involves discipline.

In other words, global warming is best compared to a chronic condition that requires monitoring so as not to get worse. It is like obesity. If we don’t address it, global warming will cause a significant deterioration in the quality of life for many humans. If we consume empty calories we will live with the consequences for a long time. Regardless of how we arrived here (and it is pointless to argue whether our condition was predestined or chosen) the course of action we must take is fairly clear.

And just as someone who is obese has a greater challenge than an alcoholic or drug addict (who stops taking the substance completely, while the obese person must still let the tiger out of the cage and eat three times a day), we are in the situation where we must address the problem while knowing that our energy consumption will undoubtedly increase for the first three quarters of this century, before population and development begin to stabilize.

The planet does not have a fever. The patient does not have cancer. There is no correct surgery or silver bullet medication that will solve our problem. We need to change our diet–the portfolio of fuels that power our world–and learn the meaning of portion control.

Our problem is less lethal than climate activists portray–but its solution is more complex than any of us would like.

Finding new data and incorporating it in support of or opposition to theory is the way science works–and it works very well. We live in an amazing and wonderful world because of it.

The term ‘climate science’ is actually an umbrella phrase that covers a number of disciplines that contribute to our overall understanding of the many forces acting and interacting on our climate. Some of these disciplines are mature–like physics. Others are not.

Many of the participants in the political debate about what to do regarding future climate change do not understand this. Many others are conversant with one of the sub-topics and think that allows them to speak with authority on other topics. The result is dismal–and what you see around you.

James Hansen is both a champion and icon of climate activism. A respected scientist (I certainly respect him), he has been tireless in attempting to raise awareness of the possible effects of global warming and the human emissions that contribute to it. Sometimes he has gone overboard–but that’s a bit to be expected in a cause that he sincerely believes to be of utmost importance to us all.

He recently published a very short note acknowledging that temperatures have not risen over the past decade. There’s something in it that we might find of interest: “The 5-year mean global temperature has been flat for a decade, which we interpret as a combination of natural variability and a slowdown in the growth rate of the net climate forcing.”

He explains later, “It should be noted that the “standstill” temperature is at a much higher level than existed at any year in the prior decade except for the single year 1998, which had the strongest El Nino of the century. However, the standstill has led to a widespread assertion that “global warming has stopped”. Examination of this matter requires consideration of the principal climate forcing mechanisms that can drive climate change and the effects of stochastic (unforced) climate variability.

“The largest climate forcing is caused by increasing greenhouse gases, principally CO2 (Fig. 5). The annual increment in the greenhouse gas forcing (Fig. 5) has declined from about 0.05 W/m2 in the 1980s to about 0.035 W/m2 in recent years 8. The decline is primarily a consequence of successful phaseout of ozone-depleting gases and reduction of the growth rate of methane. Also, the airborne fraction of fossil fuel CO2 emissions has declined and the forcing per CO2 increment declines slowly as CO2 increases due to partial saturation of absorption bands, so the CO2 forcing growth rate has been steady despite the rapid growth of fossil fuel emissions.”

As I have written previously, fossil fuel emissions haven’t ‘grown rapidly’–they’ve exploded. According to CDIAC, one third of all human emissions in history have occurred since 1998–right when temperatures stopped rising.

Taking Hansen at his word (and I do and I think you should, too), we get an inkling of something important, but as yet not explicitly said.

Of course CO2 concentrations contribute to warming–that’s basic physics, using the same calculations that make our modern world possible. But they are not the control knob on the dashboard that is the prime mover of temperatures. Hansen himself writes about solar variability, aereosols (which might be increasing as the developing world continues industrialization), the relative proportion of El Nino to La Nina years, and of course the natural variability that is always present even when we cannot define it.

CO2 is one actor. Not the only one and perhaps not even the most important one. With recent stories about black soot being an easier problem to solve, perhaps this is legitimizing language from the climate guru himself–climate change has many causes. Some of them are our responsibility. One is CO2. Another is pollution, another is deforestation, another is other land use changes. Some of the causes of climate change are not human-caused.

This should encourage us to look at what we can do most effectively in the short term.

Look–I’m not suggesting that we abandon the fight against CO2 emissions. Nor am I suggesting that global warming has gone away. But here, in an important document written by a highly respected climate scientist, is essentially implicit permission to look at all of the causes and all of the potential solutions.

I’ve been writing for several years now that this would be the toughest decade for climate activists. My reasoning has been that the economics of the prescriptive measures being pushed would become clearer (and people would start to understand how expensive fighting climate change really is) and that many of the factors that worked to push temperatures up in the last decade have switched modes–the alphabet soup of AMO, PMO, ENSO, accompanied by solar cycles, etc.

I even bet climate activist Joe Romm $1,000 that this decade wouldn’t warm more than 1.5C, based just on the changes in these factors. I still think I’m going to win.

There’s been a lot of pushback, but uber climate scientist James Hansen made it official the other day–temperatures are not rising. Temperatures have stalled. He writes, “The 5-year mean global temperature has been flat for a decade, which we interpret as a combination of natural variability and a slowdown in the growth rate of the net climate forcing.”

And so begins a decade when activists will have to fight twice as hard just not to lose ground. They couldn’t convince everyone back when temperatures actually were rising quickly–it will only be tougher now. (Which is one reason that tying their fortunes to their new pet toy Xtreme Weather is idiotic.)

Their real best bet? They need to make the following point early and often: If all of the cyclical or periodic components that drive the weather are pushing in a downward direction–and temperatures don’t fall–this global warming stuff is not only real, but probably pretty powerful.

So far I have read only their prefatory Letter to the American People, found here. There are elements of this letter that I believe to be scare talk not founded in fact. In fact, some of it seems hyperbole written with the intent to frighten the American people rather than inform them.

Their opening sentence qualifies in that regard: (2) “Climate change, once considered an issue for a distant future, has moved firmly into the present.”

Contrast that with the statement from the Intergovernmental Panel on Climate Change’s SREX, or special report, issued in March of 2012: “There is… high agreement that long-term trends in normalized losses (due to extreme weather) have not been attributed to natural or anthropogenic climate change.” Later in the report we read, “…droughts have become less frequent, less intense, or shorter, for example, in central North America and northwestern Australia,” and “There is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at regional scales because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering. Furthermore, there is low agreement in this evidence, and thus overall low confidence at the global scale regarding even the sign of these changes.”

The IPCC also writes “Increasing exposure of people and economic assets has been the major cause of long-term increases in economic losses from weather- and climate-related disasters (high confidence). Long-term trends in economic disaster losses adjusted for wealth and population increases have not been attributed to climate change, but a role for climate change has not been excluded.”

The Letter to the American People continues: “(11) Americans are noticing changes all around them. Summers are longer and hotter, and periods of (12) extreme heat last longer than any living American has ever experienced.”

This is not true. There are over 6 million Americans alive today who experienced summers as long and hot, with great periods of extreme heat in the mid-1930s, when the Palmer Drought Index was the same as current periods, and tens of millions more who saw the mid-70s, when drought conditions were almost as high. Drought is a cyclical event that is experienced throughout large sections of the United States and has done so since pre-historical times.

If the National Climate Assessment and Development Advisory Committee is going to trumpet false but frightening findings to the American People in the introduction to its report, what will the rest show us?

The global discussion on climate and man’s effects on it is badly stalled.

Perhaps that’s because temperature rises have stalled as well. Since the grand El Nino of 1998 there hasn’t been much in the way of temperature climbs. If this pause continues a while longer scientists will have to rethink how they construct their models. A lot of climate activists are fighting to preserve the continuous climbing idea. They point to the fact that the plateau does not include a decline and quite rightly point out that if natural causes are masking the contributions of CO2, it doesn’t really mean that those contributions aren’t there. Sadly, a lot of their energy is wasted on trying to defend over-ambitious statements of years gone by–and it shows.

On the other side of the fence, skeptics are chewing like a terrier at the pant cuffs of the climate establishment, still fighting the FOI fight and pointing out the flaws and the foibles of those involved in the Climategate scandelette. There’s real material for them to focus on, but it seems almost quaint in 2013. At the end of the day, skeptics will probably get an acknowledgment of wrong-doing with regards to the hiding the uncertainty of data presented to policy makers. But at the end of the day it will no longer be relevant. And the fact that the investigations and continuing procedures were probably set up to achieve this exact result will not change it.

Here in the present day, climate activists are stupidly and wrongly trying to tie current weather events to climate change. Stupid, because it is bad strategy to make yourself a hostage to the weather. Wrong because scientists from all walks of life have said repeatedly that you cannot tie individual events to climate change. (That includes the IPCC.) Worse, a lot of the metrics used in this silly attempt are actually proving to show that there are fewer destructive events, such as hurricanes and tornados and that some measurements of drought show it in decline in many (not all) major agricultural areas.

It’s all trivia–if the skeptics secured the resignation of those they are attacking it would not change climate science, climate policy or the climate itself. If the activists managed to convince the world that each storm or drought was a plague visited on the people by climate change it would not affect the policy decisions of the countries affected, let alone policies of countries far away.

Even if atmospheric sensitivity is low–and I think it is–the trends for energy consumption and fossil fuel usage threaten to get to really high levels between now and 2075, something I talk about a lot at my other blog. Tough and important decisions need to be discussed, made and implemented.

Chasing after those who behaved badly in the past, inventing a connection between today’s storms and climate change–this is slowing us down, not helping.

At the request of the guest author I have removed some posts and comments from this blog. They comprised the memoirs of a scientist. I will hopefully write more about his decision and the factors that led to it later.

I first became interested in the subject of climate change after reading Bjorn Lomborg’s ‘The Skeptical Environmentalist’ and watching him get dragged through the mud by a concerted attack on him by environmentalists.

I started to read more about the subject, starting with the environmentalists’ attacks on Lomborg. (At the time I was evaluating which of two areas–energy or healthcare–that I would dive into in an attempt to become a subject matter expert for career purposes. I had been specialized in high technology since 1996 but felt the need to add a vertical sector, very much in the same way that a lawyer might branch out from dispute resolution to include family law. Both healthcare and energy are rapidly becoming high technology enterprises and I wanted to watch the effects of high tech as well as its development.)

After two years of reading I opened a short-lived weblog called The Liberal Skeptic, which quickly morphed into a column written for Examiner.com. Climategate happened as did a physical move back to the U.S. and career changes. I co-authored a book on Climategate, abandoned the Examiner column and spent a couple of years commenting and guest posting on skeptical weblogs. In January of 2012 I opened a weblog on energy consumption called 3000 Quads and in December opened this weblog focused on putting forth the rather nebulous ‘Lukewarm’ message.

I’m describing the timeline of my involvement in climate issues to highlight a specific point–there was not enough time for a decent learning curve in there.

I started off fairly skeptical of the climate conventions, because the nature of the attacks on Bjorn Lomborg were so… well, underhanded is the politest term I could use, that I really thought that climate science must not have anything else on the shelf to offer humanity if they had to resort to such tactics.

But the U.S. Navy had taught me physics and enough ‘higher’ math to understand the equations and some acquaintances I made walked me through the various equations needed to understand the basics of climate change and, more importantly, to see how the inputs to those equations were arrived at.

Climate change caused by human factors was clearly more than possible–it seemed all too probable. The real questions turned to how much, how long, the effects and our policy options.

But again, this was a forced learning curve, with lots of hurried reading and decisions on what books, papers and articles I would put off for another day. At the end of the day I would estimate that I’ve read about 10% of what I marked out as needed reading. Maybe at some point I’ll make a list of what I have read so far–it ranges from popular literature from Al Gore and Ian Plimer, equally unhelpful, to the Intergovernmental Panel on Climate Change’s AR4, which is an extremely useful document.

This year will mark the publication of the IPCC’s AR5, but also a large number of other papers and compendia on the subject. Preceding AR5 is the very recent publication of an 1,100 page draft report by the National Climate Assessment and Development Advisory Committee on climate. As the AR5, leaked and available here, is also a long document, this will be a reading–and hopefully learning–year for me. (I will also report here on what I read and how it changes my thinking, if at all.)

Don’t get me wrong–I stand by 99% of what I’ve written with regards to climate change, and have hopefully apologized for the errors I have made in print already. I’ve interviewed the late Stephen Schneider, John Christy, both Pielkes and a number of other climate scientists. I’ve read dozens of books and hundreds of papers and thousands of blog posts. But I recognize that I want to learn more.

This is the right year to learn more. (Is there a wrong year for that?)

At Rabett Run, Josh Halpern is hiding behind the skirts of MathBabe to accuse skeptics of the crimes of which he and many other climate bloggers are guilty.

And over at Planet 3, next to an award for journalistic horribleness given to David Rose of the UK Daily Mail, is the most honest headline in the climate change blogosphere on January 11, 2013: “Nothing New on the Global Warming Front“.

We saw earlier that the often cited plateau in global warming (16 years with no real change in global temperatures) was not enough to get anybody’s attention–but that when it was combined with the statistic that we had emitted one third of all human CO2 since that plateau started, it got a few people to scratching their heads.

That’s because the numbers tossed around in climate discussions are too disconnected from human experience to mean much of anything to anybody. I can tell you what a quad is–it’s a quadrillion BTUs. Do you feel smarter knowing that? I can explain it in greater detail. In fact I have, with quads looked at here and BTUs here.

But people have been using raw numbers to talk about climate change for a long time and they’re not playing fairly. I’ve seen numbers abused a lot, especially when talking about the loss of ice in Greenland and the Arctic. People talk about billions of tons lost or how many Manhattans of ice were formed last week.

What they should do is just refer to percentages of the estimated total. But if they did that, people would realize that fears of a melt-out in Greenland or Antarctica is simply absurd. Or that the rapid regrowth after a truly amazing summer melt in the Arctic isn’t really very encouraging.

With that in mind, let’s put two recent statistics together. According to a World Bank report released on January 18, 2012, the GDP of the world grew by an anemic 2.6%. Ho, hum. We all want better.

According to the Global Carbon Project, human emissions of CO2 grew by 2.6% in 2012. Boo. We want that figure to drop.

If you put those two statistics together and actually read the reports that generated the statistics, you see other things. First and most obviously, GDP grew at the same rate as than emissions. Think how bad we would feel if emissions were rising more quickly than CO2…

The Global Carbon Project says that emissions increased by 3% in 2011–funny how the headline of the article says ‘No Slowdown in CO2 Emissions in 2012’. To me, 2.6% is indeed lower than 3%, but maybe they’re doing ‘climate math’, where the point you’re making can be disconnected from the numbers.

The real point is that emissions are not outpacing development. Restraint, taxes and the growth of natural gas and renewables in the developed world are making it possible for the developing world to improve their style of life without the larger scale emissions of CO2 that characterized our historical development.

Now, we know that we have to bend the curve more. Perhaps because curmudgeons are not celebrating the success of the U.S. in lowering emissions, the goal of doing just that still seems unattainable.

But if the huge economy of the U.S., profligate in its consumption and careless in the past about its emissions, can reduce emissions, so can the rest of the world.

The hydraulic fracturing for the purpose of capturing natural gas is having a real impact in the United States.

Not just on the portfolio of fuels used to generate our energy (coal-fired power generation is falling dramatically and fracked natural gas is taking up the slack enthusiastically).

Fracked natural gas is changing the discussion on climate change, both qualitatively and quantitatively.

Because natural gas emits about one half the CO2 as coal when burned, the portfolio switch from coal to natural gas has allowed a significant improvement in U.S. emissions, which have fallen to 2007 levels despite continued economic and manufacturing growth.

The reaction of climate activists is to basically say ‘It doesn’t count! Gas still emits CO2!’ More reasonable people offer their thanks and the hope that natural gas can serve as a bridge fuel that tides us over until some combination of nuclear and ‘true’ renewables can carry a bigger part of the load.

But I’m writing about this because of the switch natural gas has caused in the conversation. I routinely look through as many climate-centered weblogs as I can and I can tell you that natural gas has caused a switch in the topics covered.

What seems more interesting to me is that the introduction of fracking to the climate conversation also seems to have opened the floodgates for discussion of other topics, ranging from the closely related subject of Arctic oil drilling to the vaguely parallel, if entirely separate, subject of the safety of GMOs.

This is a real public good. The climate conversation in and of itself has verged on a stale sterility, with the same bad actors making the same bad points–from Mann and Gleick on one end to Monckton and Morano on the other. Introducing both sub and separate topics increases the opportunity to learn, communicate–and maybe share at some point down the road.

As a Lukewarmer I should detail some specifics of the differences I hold with the activist consensus, on the one hand, and the skeptics on the other.

I am more frequent and usually more vehement in my criticism of the activist consensus. I think this is appropriate for two reasons. The first is the consensus holds all the levers of power. They are educating our children, hold the decision-making votes for funding of research, they have instant access to a compliant media (well, outside of Fox), etc. They need to be held to account for mistakes and misjudgments, and the skeptics aren’t really doing a good enough job of that. And sprinkling their essays with the occasional Latin phrase doesn’t change it.

The second reason is that the consensus activists have personally and professionally attacked anyone who opposes the consensus, using crude and vicious tactics and unethical behavior. From Ben Santer threatening to beat the crap out of Patrick Michaels to Peter Gleick’s theft and forgery of opposition documents, they have misbehaved. As they are not cleaning up their side of the fence, I and others will continue to oppose them vigorously.

Here’s a selection of what I’ve written on the subject, taken from comments on other weblogs:

“As long as ‘communication’ means nothing more to the consensus than finding the most persuasive argument or choosing the right channel for their messages, those repeating these arguments will sound exactly like the marketing and advertising moguls I have advised since 1996.

But something happened since then and some of these moguls noticed. They found Web 2.0 tools gave them a chance to listen to what their customers (and more importantly the people they wanted to become their customers) were talking about. What was important to them, their opinions on things that weren’t related to the marketers’ products, etc. And some of these people ventured to actually engage in a dialogue with them. And a funny thing happened. Many of them began to win in the marketplace.

But the fact remains that in April of 2012 none of you show any signs of having listened to either your opponents or the vast majority of people who are steadfastly staying out of this argument.

Scientists are not necessarily bad communicators. But they have abdicated their chance and disastrously have let people like Eli Rabett pretend they can communicate on scientists’ behalf. For every good scientific communicator like James Hansen and Bart Verheggen, there are covens full of Eli Rabett,Michael Tobis, Tim Lambert and Joe Romm. Not to mention their groupies. The result is what you see around you.

Scientists have to grab the microphone out of the clutching hands of the wannabees and politically motivated.

It was no journalist who made the No Pressure video. It was no journalist who told skeptics that Green Peace knew where they lived. It was no journalist who wrote Anderegg, Prall et al. It was no journalist who ignored an IPCC scientist and continued to insist that Himalayan glaciers would disappear before 2035–while bidding on a project to study melting Himalayan glaciers. It was no journalist who said that the streets of Manhattan would be underwater in either 20 or 40 years. It was no journalist who told fellow scientists to delete all emails regarding AR4. The list could go on for days.

The consensus apologists have run out of feet to shoot themselves in, so they frantically cast about looking for scapegoats. And after 25 years of journalists from the BBC, the Guardian, the NY Times and every other major media outlet printing their screeds and screeches on demand, why it must be their fault!

What’s going on is no fault of the journalists (there are a handful of exceptions out of thousands writing on the subject). Overall, there is no public issue that ever received more of a free pass than climate science did from the overwhelming majority of journalists and media outlets. To say otherwise is basically an attempt to perpetuate a big lie, which I won’t capitalize in deference to Mr. Godwin.

Most people believe in the basic science of global warming. Most people are not certain about the effects of global warming predicted by people like Phil Jones, Michael Mann, Peter Gleick and Eli Rabett. And that’s due to what these people write and say.

I believe that the consensus side needs to adhere to much higher standards of ethics, behavior and, yes, manners than those who oppose them, and I certainly don’t believe the consensus side has succeeded in that. The consensus side holds the positions of authority, holds the data, holds the levers of power. The consensus side decides what research is funded and performed and which is publicized in a largely complaisant media. But instead of acting like grownups, they pretty much fit Donna LaFramboise’s skeptical description as spoiled teenagers.

Finally, I personally think the real avoidable tragedy that has led us to this impasse has been the willingness of climate scientists to allow others to speak for them. I fully understand that they are busy and that they didn’t become scientists because they wanted to stand in front of a microphone or under klieg lights. But the fact is that the people who jumped on stage in their absence did an absolutely horrible job–and are still doing so.

I think the best thing that could happen would be for scientists–and only scientists–to organize a media team that wasn’t searching for climate heresies but was actively promoting real research results. And their first order of business would be to clear out the stables of the so-called champions who in fact have just about wrecked any chance of moving forward.

I would offer the reminder that we have had people in the past who were able to communicate science effectively, ranging from scientists (Sagan et al) to science writers to science fiction writers.

They were able to both engage and transfer knowledge on subjects as varied and controversial as eugenics, nuclear war and racial equality to topics as arcane and (at first glance) un-noteworthy as demographics.

Some of the topics were very much in dispute at the time of discussion by these communicators–some just as vehement as the current discussion of climate change.

I see no evidence that would-be communicators of the climate consensus have even referred to the available lessons from the past, let alone adopted them.”

The theory of global warming is solid, staid and uncontroversial. All things considered, if we double the concentrations of CO2 in the atmosphere, temperatures should increase by 1.1C over what they otherwise would have been.

The theory of atmospheric sensitivity is a different story. The political controversy that has raged since 1988 centers on the idea that our atmosphere is sensitive to changes and that changes produced by humanity–in particular our emissions of greenhouse gases–will cause more warming than just the 1.1C from the emissions themselves.

We don’t know what sensitivity is. In fact, there is more than one type of sensitivity and more than one definition. That doesn’t help matters.

Real Climate, the ‘voice’ of the climate establishment (that’s not meant to be a criticism, btw) has two posts up now on sensitivity. In their first post they acknowledge the difficulty of definitions:

“In practice, people often mean different things when they talk about sensitivity. For instance, the sensitivity only including the fast feedbacks (e.g. ignoring land ice and vegetation), or the sensitivity of a particular class of climate model (e.g. the ‘Charney sensitivity’), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1% increasing CO2 after 70 years). As you might expect, these are all different and care needs to be taken to define terms before comparing things (there is a good discussion of the various definitions and their scope in the Palaeosens paper).”

The post talks about some recently published papers and ends with what appears to me to be a basic concession–that current thinking places sensitivity within a lower range than previously thought.

The IPCC has held that the likely range of sensitivity values are between 1.5C and 4.5C, writing in their Fourth Annual Report (known as FAR):

“The likely range[1] for equilibrium climate sensitivity was estimated in the TAR (Technical Summary, Section F.3; Cubasch et al., 2001) to be 1.5°C to 4.5°C. The range was the same as in an early report of the National Research Council (Charney, 1979), and the two previous IPCC assessment reports (Mitchell et al., 1990; Kattenberg et al., 1996). …”

we conclude that the global mean equilibrium warming for doubling CO2, or ‘equilibrium climate sensitivity’, is likely to lie in the range 2°C to 4.5°C, with a most likely value of about 3°C. Equilibrium climate sensitivity is very likely larger than 1.5°C.

For fundamental physical reasons as well as data limitations, values substantially higher than 4.5°C still cannot be excluded, but agreement with observations and proxy data is generally worse for those high values than for values in the 2°C to 4.5°C range.”

Real Climate concludes its first post by writing “In the meantime, the ‘meta-uncertainty’ across the methods remains stubbornly high with support for both relatively low numbers around 2ºC and higher ones around 4ºC, so that is likely to remain the consensus range.”

Their second post details recent work that attempts to work around our ignorance of cloud feedbacks and comes up with a high figure (4C) for sensitivity that doesn’t include cloud effects. (I don’t find it convincing–but I’m not a scientist and my lack of conviction on this is based on other data, not that which they looked at–caveat lector.)

Now, the very probable reason that Real Climate has published two posts on climate sensitivity at this time is that conflicting work has recently seen the light of day that points at lower levels of sensitivity. (This is the way the political fight around climate change works–the activists have a ‘rapid response team’ that springs into action when questions arise or conflicting data is published. There in all honesty appears to be a coordinated campaign to drive an agenda, something that they in turn accuse skeptics of doing.)

Matt Ridley, author of The Rational Optimist, highlighted recent work by Nic Lewis, who used observational data to postulate that a doubling of CO2 will lead to a warming of 1.6°-1.7°C (2.9°-3.1°F). Ridley’s piece was also published in the Wall Street Journal. The articles (and a vehement, if knee-jerk, response by Joe Romm, was discussed at Bishop Hill’s blog here, here, here and elsewhere.

My own contribution to the debate, published in my other weblog here, is based on decidedly lower math. I noted that during the recent (hotly debated) plateau in temperatures, humankind has managed to emit one third of all the greenhouse gases they have ever spit into the atmosphere–without any tangible effects on temperatures. Now, climate science allows for uneven steps in temperature change, and I am perfectly comfortable with that. The current warming period is certainly characterized as a sawtooth form imposed on a rising trend. It is conceivable that this is just another pause that will be followed by another period of temperature rises.

But this pause in the temperature rises has lasted longer than previous pauses. Since 1998 there has been little if any net rise in temperatures. Should this pause continue for just a few more years it will mathematically invalidate many of the climate models’ predictions.

And it almost beggars belief that the sheer quantity of emissions since 1998 can have so little effect–if sensitivity is high. On the other hand, if sensitivity is as low as Nic Lewis postulates (as have others before him), it would make more sense that a massive outgassing of CO2 in a short timeframe could still have a small effect.

What we’re left with is the realization that this period will be the proving ground for the various theories of sensitivity. Global emissions are hardly likely to go down–indeed, they will probably continue to increase, as developing countries continue to burn incredible quantities of coal in their race to provide modern lifestyles to their citizens. By the end of the decade humanity will have emitted one half of their historical total of greenhouse gases since 1998.

The results will be interesting. If the current temperature plateau holds, the climate activists will have to maintain that the lag between emission and response is so great that previous temperature rises were quite possible linked to other phenomena than human CO2–or else revise their sensitivity figures.

If, on the other hand, temperatures begin once again to rise quickly, many skeptics will have to acknowledge many uncomfortable conclusions of the climate scientists they have been fighting so bitterly.

In either case, this decade will provide something the debate has sorely needed for 25 years–answers.